WordPress VIP support will not allow this plugin to be used until this issue is addressed:

models/ajax/formatpiecesetsprite.php

On the generateSprite method, the image is not being sideloaded, which means that will not work properly as it won't be copied to the CDN. Should be used media_handle_sideload or wp_upload_bits alongside with apply_filters( wp_handle_upload, $file_upload ) to create a new attachment. You can take a look at the Watermark plugin for examples: https://vip-svn.wordpress.com/plugins/watermark-image-uploads/watermark-image-uploads.php